1. Field of the Invention
The present invention relates to a dry-sump engine, and more particularly for a planing boat or watercraft, e.g., a small personal watercraft.
2. Description of the Background Art
Heretofore, two-cycle engines have generally been used as power sources for small planing boats or watercraft. However, the use of a four-cycle engine has been examined recently for accommodating low-pollution and noise reduction requirements.
In a small, planing boat, a compact engine is required because the engine is stored in a small space defined by a hull and a deck arranged in a substantially sealed state. However, the four-cycle engine tends to be large and cumbersome because a cylinder head having a dynamic valve system is often disposed in the upper part of the engine, and an oil pan is disposed in the lower part of the engine, see, e.g., Japanese Patent Publication No. 2754371.
The present invention overcomes the shortcomings associated with the background art and achieves other advantages not realized by the background art.
An object of the present invention is to provide a dry-sump engine for a planing boat or watercraft that reduces the overall height of the engine.
One or more of these and other objects are accomplished by a dry-sump engine for a planing boat having a jet propulsion pump, the dry sump engine comprising a crankshaft extending along an axial centerline of the engine; an upper case and a lower case of the dry-sump engine; at least one fastening bolt securing the upper case and the lower case of the engine along a parting plane; an oil pan, the lower case including a mounting face for joining a joint surface of an oil pan and being provided in a position below the parting plane, wherein the fastening bolt is positioned higher than the oil pan with respect to the parting plane and the mounting face surrounds the at least one fastening bolt when viewed with respect to a bottom portion of the lower case and the engine centerline.
One or more of these and other objects are further accomplished by, in combination, a dry-sump engine and a planing boat, the engine driving a jet propulsion pump for the planning boat and being arranged in a vessel body of the boat and surrounded by a hull and a deck, the engine comprising a crankshaft extending along a length of the vessel body and in parallel with a centerline of the engine; an upper case and a lower case of the dry-sump engine; at least one fastening bolt securing the upper case and the lower case of the engine along a parting plane; an oil pan, the lower case including a mounting face for joining a joint surface of an oil pan and being provided in a position below the parting plane, wherein the fastening bolt is positioned higher than the oil pan with respect to the parting plane and the mounting face surrounds the at least one fastening bolt when viewed with respect to a bottom portion of the lower case and the engine centerline.
In a dry-sump engine for a small planing boat according to the present invention, since an engine for driving a jet propulsion pump is arranged in the vessel body surrounded by a hull and a deck so that the crankshaft thereof extends along the length of the vessel body, and a mounting face for an oil pan is provided in the outside vicinity of a fastening bolt for fastening an upper case and a lower case of the engine that support the crankshaft when viewed from the bottom, the overall height of the engine may be reduced.
If the mounting face for the oil pan is provided inside the fastening bolt when viewed from the bottom, the capacity of the oil pan is reduced. If the mounting face is provided outside the fastening bolt at a distance therefrom, the width of the oil pan increases, and thus it can hardly be fitted to the configuration of the vessel. Further, if the mounting face for the oil pan is overlapping the fastening bolt when viewed from the bottom, the overall height of the engine increases correspondingly.
Since the mounting face for the oil pan may be provided in the outside vicinity of the fastening bolt when viewed from the bottom in an embodiment of the present invention, the overall height of the engine may be reduced. In addition, the oil pan may be provided while securing an appropriate capacity, while being adapted to the bottom of the vessel body, and by securing an appropriate clearance with respect to the vessel body.
Since the engine for driving a jet propulsion pump may be disposed in the vessel body surrounded by the hull and the deck, the engine is provided with an oil pan below the crankshaft, and a strainer is provided in the vicinity of the engaging surface between the oil pan and the engine along the engaging surface. The overall height of the engine may be reduced while securing the area of the strainer.
Since the strainer may be provided integrally with the oil pan, the strainer can be mounted simultaneously with the oil pan. Since the portion in the vicinity of the bottom of the oil pan and an oil pump provided at the end of the crankshaft may be brought into communication with each other with a joint pipe in the dry-sump engine, oil filtered through the strainer is directly guided into the oil pump. Therefore, the entry of foreign matter and contaminates into the oil pump is prevented, thereby improving durability of the oil pump.
Since the oil pump is provided at the end of the crankshaft, and an oil exit in communication with the oil-pump is provided on the oil pan at the end in the axial direction of the crankshaft, the overall height of the engine can be reliably reduced in comparison with the case where the oil exit is provided for example at the bottom of the oil pan.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.